The present invention relates to key switches, and more particularly to a key switch having a key or pushbutton made from an outer layer and an inner layer where the inner layer bears some indicium and the outer layer protects and magnifies the indicium. The invention further relates to a game controller incorporating the inventive key or pushbutton.
A variety of electric and electronic devices use keyboards, key pads, or pushbuttons. For example, a personal computer may have a keyboard, a mobile or cellular telephone may have a key pad, a public telephone may have a key pad or series of pushbuttons, and an electronic game controller may have pushbuttons. In each of these electronic devices, keyboards, key pads, and pushbutton assemblies, a key is depressed to activate a switch.
A key generally has indicia or indicium to indicate the function of the key. The indicia or indicium (hereafter, xe2x80x9cindiciumxe2x80x9d) can be letters, numbers, symbols, words or other indication of the assigned function to the key. The indicium can be painted on a top surface of the key so that a user can determine the function of the key. The problem with painted keys is that the indicium paint can wear-off leaving the user without means to readily determine the function of the key. This problem is particularly prevalent in applications subject to highly repetitive use and/or heavy duty use. One example, of a highly repetitive use application is a public telephone in a popular area where the telephone is subject to frequent use. Public telephones can also be subject to heavy duty use, including abuse, as well as, being subject to outdoor environmental elements. In these instances, paint on the keys indicating each of the key""s numerical value can and often does wear off. An example of both high use and heavy duty use, is a game controller device where the use is highly repetitive, and the use is increasingly hard with escalating enthusiasm for the game.
To avoid the problem of the indicium paint wearing-off, manufacturers have made keys from different colored materials. In this instance, one material protrudes through a second material at the point of the indicium. The second material has through-openings delineating some indicium, and the first material fully protrudes into these through-openings. For example, FIG. 3B of U.S. Pat. No. 5,172,990 to Weng, shows a push-button 5 having a face plate 55 and bottom portion 56 where face plate 55 has holes conforming to the shape of letters or Arabic numerals 561. Weng represents that letters or numerals of this type of push-button key will not become obscured or blurred after a prolonged usage of the key (col. 3, lines 18-29). A drawback of the key of Weng is that the indicium is exposed to the surface. While the exposed indicium may not rub-off like paint, the indicium may still become fouled, particularly around a periphery of the indicium where the two materials meet. Over time the juncture between materials may enlarge due to wear and relative movement between the face plate and bottom portion creating a crevasse for contaminants. Furthermore, the exposed indicium may be difficult to discern due to the seemingly small size of the indicium.
In small electronic devices, hand-held devices, and devices that have a large number of keys arranged closely together, small size indicia are particularly problematic. U.S. Pat. No. 5,635,927 to Lin discloses an illuminated key cap having a plano-convex lens for showing a key identification pattern in an enlarged scale. A bottom wall II of the plano-convex lens is covered with a light blocking ink. This light blocking ink is laser engraved to define a non-ink pattern 12 in which light is allowed to pass. Viewed from the top, the convex wall outer surface of the key cap is said to cause the pattern 12 to be viewed in an enlarged scale (col. 3, lines 23-27). The problem is that this key cap is difficult to manufacture because the key cap is made from at least two separately produced parts. One of the parts is subject to the steps of photo-resist inking and laser engraving. That part must then be bonded together with the second part, sandwiching the remaining portions of the photo-resist layer at the interface. It appears that this mix-match of materials at the interface of the two separately produced parts could lead to separation of the parts over time. Accordingly, a key that overcomes the problems and disadvantages of the prior art is needed.
It is an aspect of the present invention to provide a highly legible key. Keys that have top quality visible characteristics are highly desirable in performance and precision applications.
It is another aspect of the present invention to provide a highly durable key. A key that maintains the functional and aesthetic qualities throughout the life of an electronic device in which the key is employed is needed.
It is yet another aspect of the present invention to provide a key that maintains legibility of the indicium and maintains its aesthetic qualities throughout highly repetitive and heavy duty use. A key that maintains its indicium and aesthetic qualities is very desirable in the console or controller gaming industry.
It is a further aspect of the present invention to simplify the manufacturing steps for making a key. Still further, it is an object to eliminate manual assembly steps for making a key and provide a key suitable for high volume production, and thus, reduce the manufacturing costs associated with making keys.
According to another aspect of the present invention, there is provided a key comprising an outer layer and an inner layer. The outer layer and the inner layer may be an outer shell and an inner core, respectively. The outer layer is formed such that an inner surface of the outer layer has a recess delineating a negative form of the desired indicium. The inner layer is formed to the interior of the outer layer and fills the negative form of the desired indicium. The outer layer is formed of transparent or translucent material such that the material of the inner layer is visible through the outer layer. In this manner, the outer layer protects the indicium from wear and from fouling. The outer layer can be tinted to improve key identification and discrimination such as by color recognition. The key can also be tinted to add to the aesthetic appearance of the key and of the electronic device in which the key is employed.
Accordingly to another aspect of the present invention, the inner layer of the key is formed of a material such that the indicium is readily discernable through the outer layer. In this manner, the material may be opaque or tinted, and the color selected for aesthetic appearance of the key, and for color complement or contrast with the outer layer and surrounding electronic device casing.
According to another aspect of the present invention, the outer surface of the inner layer may be curved or domed in the region of the indicium. This curve or dome in the region of the indicium allows the key indicium to be easily viewed from the side of the key, as well as, directly overhead.
According to yet another aspect of the present invention, an outer layer with a domed exterior surface may be further desirable in that the dome can impart a level of magnification to the indicium located below the domed exterior surface.
According to still another aspect of the present invention, the outer layer has a tip portion axially aligned with a base portion. A step or a ledge can be created at the juncture of these two portions that is useful for retaining the key within an opening in an electronic device casing. The tip portion may be elliptical or oval shaped and the base portion may be cylindrically shaped.
According to another aspect of the present invention, the dome exterior surface of the outer layer is positioned along a sloping line. Positioning the dome along a slope improves finger-to-button contact by creating a larger dome surface area ensuring that a user engages the key when the user""s fingers are moving generally horizontally across a surface of an electronic device casing.
According to still another aspect of the present invention, the key may be formed from the same type of polymer though of different colors or transparencies. The key may be formed by a two-shot molding sequence where a first mold is provided to form the outer layer and then a second mold is provided to form the inner layer. The outer layer is used to form an outer part of the second mold.
Further, the key may include a tab for retaining the key in an electronic device casing. The tab and the step or ledge are for engaging a structure of an electronic device casing, such that, the key can not misalign and dislodge from the electronic device.
According to another aspect of the present invention, the key includes an inner layer having a web. The web can be used for depressing a flexible contact switching assembly. The web may be recessed in the outer layer for centering the contact switching assembly with the key.
Other aspects and features of the invention will be more fully understood from the following detailed description and appended claims when taken with the accompanying drawings.